The paper by Mr. Leem and Prof. Kitagaki has been accepted in Macromolecular Symposia.

This study analyzes the physical changes in foam plastic insulation materials under different humidity conditions, focusing specifically on degradation due to moisture. Foam plastic insulation is expected to be installed in buildings, but it has been reported to absorb moisture and consequently increase thermal conductivity in high humidity environments. The paper demonstrates through visualization of moisture distribution with X-ray CT, measurement of moisture absorption, and changes in relative thermal resistance ratio under humidity cycles, that PF (phenolic foam) shows significant moisture absorption compared to XPS (extruded polystyrene foam) and PUF (polyurethane foam), and that the thermal performance of these insulation materials can be affected by humidity over the long term.

https://onlinelibrary.wiley.com/doi/10.1002/masy.202100218